Conductive oxide overhang structures for oled devices

ABSTRACT

Sub-pixel circuits and methods of forming sub-pixel circuits that may be utilized in an organic light-emitting diode (OLED) display are described herein. The overhang structures are permanent to the sub-pixel circuit. The overhang structures include a conductive oxide. A first configuration of the overhang structures includes a base portion and a top portion with the top portion disposed on the base portion. In a first sub-configuration, the base portion includes the conductive oxide of at least one of a TCO material or a TMO material. In a second sub-configuration, the base portion includes a metal alloy material and the conductive oxide of a metal oxide surface. A second configuration of the overhang structures includes the base portion and the top portion with a body portion disposed between the base portion and the top portion. The body portion includes the metal alloy body and the metal oxide surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application which claims priority toU.S. patent application Ser. No. 17/935,770, filed Sep. 27, 2022, whichis a continuation of U.S. patent application Ser. No. 17/662,960, filedMay 11, 2022, which is a continuation of U.S. patent application Ser.No. 17/647,214, filed Jan. 6, 2022 which is a continuation of patentapplication Ser. No. 17/389,934, filed Jul. 30, 2021, which claimsbenefit of U.S. Provisional Patent Application No. 63/179,074, filed onApr. 23, 2021, the contents of which are herein incorporated byreference.

BACKGROUND Field

Embodiments described herein generally relate to a display. Morespecifically, embodiments described herein relate to sub-pixel circuitsand methods of forming sub-pixel circuits that may be utilized in adisplay such as an organic light-emitting diode (OLED) display.

Description of the Related Art

Input devices including display devices may be used in a variety ofelectronic systems. An organic light-emitting diode (OLED) is alight-emitting diode (LED) in which the emissive electroluminescentlayer is a film of an organic compound that emits light in response toan electric current. OLED devices are classified as bottom emissiondevices if light emitted passes through the transparent orsemi-transparent bottom electrode and substrate on which the panel wasmanufactured. Top emission devices are classified based on whether ornot the light emitted from the OLED device exits through the lid that isadded following the fabrication of the device. OLEDs are used to createdisplay devices in many electronics today. Today's electronicsmanufacturers are pushing these display devices to shrink in size whileproviding higher resolution than just a few years ago.

OLED pixel patterning is currently based on a process that restrictspanel size, pixel resolution, and substrate size. Rather than utilizinga fine metal mask, photo lithography should be used to pattern pixels.Currently, OLED pixel patterning requires lifting off organic materialafter the patterning process. When lifted off, the organic materialleaves behind a particle issue that disrupts OLED performance.Accordingly, what is needed in the art are sub-pixel circuits andmethods of forming sub-pixel circuits to increase pixel-per-inch andprovide improved OLED performance.

SUMMARY

In one embodiment, a device is provided. The device includes asubstrate, adjacent pixel-defining layer (PDL) structures disposed overthe substrate and defining sub-pixels of the device, overhang structuresincluding a conductive oxide, the overhang structures disposed over anupper surface of the PDL structures, and a plurality of sub-pixels. Eachsub-pixel including an anode, an organic light-emitting diode (OLED)material disposed over and in contact with the anode, and a cathodedisposed over the OLED material, the conductive oxide overhangstructures disposed over the upper surface of the PDL structures extendover a portion of the OLED material and the cathode.

In another embodiment, a device is provided. The device includes aplurality of sub-pixels, each sub-pixel of the plurality of sub-pixelsdefined by adjacent pixel-defining layer (PDL) structures with overhangstructures disposed over the PDL structures, each sub-pixel having ananode, organic light-emitting diode (OLED) material disposed on theanode, and a cathode disposed over the OLED material, the overhangstructures including a conductive oxide. The device is made by a processincluding depositing the OLED material using evaporation deposition overa substrate, the OLED material disposed over and in contact with theanode, the OLED material having an OLED edge defined by defined byadjacent overhangs of the conductive oxide overhang structures, anddepositing the cathode using evaporation deposition, the overhangstructures disposed over the PDL structure extend over a portion of theOLED material and the cathode, the overhang structures including theconductive oxide.

In another embodiment, a method is provided. The method includesdisposing an overhang layer stack over adjacent pixel defining layer(PDL) structures, each sub-pixel of a plurality of sub-pixels is definedby the adjacent PDL structures. The overhang layer stack includes atleast a base layer and top layer disposed over the base layer. The baselayer includes at least one of a transparent conductive oxide (TCO)material, a transition metal oxide (TMO) material, or a metal alloymaterial. The method includes disposing a resist layer over the overhanglayer stack and patterning the resist layer to form pixel openings inthe resist layer, etching the overhang layer stack exposed by the pixelopenings to form overhang structures having a top portion correspondingto the top layer and at least a base portion corresponding the baselayer, and depositing an organic light-emitting diode (OLED) materialand a cathode using evaporation deposition such that the cathodecontacts at least a portion of the base portion.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlyexemplary embodiments and are therefore not to be considered limiting ofits scope, and may admit to other equally effective embodiments.

FIGS. 1A and 1B are schematic, cross-sectional views of a sub-pixelcircuit according to embodiments.

FIGS. 1C and 1D are schematic, top sectional views of a sub-pixelcircuit according to embodiments.

FIGS. 2A and 2B are schematic, cross-sectional views of an overhangstructure according to embodiments.

FIG. 3 is a flow a flow diagram of a method for forming a sub-pixelcircuit according to embodiments.

FIGS. 4A-4H are schematic, cross-sectional views of a portion of asubstrate during a method for forming the sub-pixel circuit accordingembodiments.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in oneembodiment may be beneficially utilized on other embodiments withoutspecific recitation.

DETAILED DESCRIPTION

Embodiments described herein generally relate to a display. Morespecifically, embodiments described herein relate to sub-pixel circuitsand methods of forming sub-pixel circuits that may be utilized in adisplay such as an organic light-emitting diode (OLED) display. In oneembodiment, which can be combined with other embodiments describedherein, the display is a bottom emission (BE) or a top emission (TE)OLED display. In another embodiment, which can be combined with otherembodiments described herein, the display is a passive-matrix (PM) or anactive matrix (AM) OLED display.

A first exemplary embodiment of the embodiments described hereinincludes a sub-pixel circuit having a dot-type architecture. A secondexemplary embodiment of the embodiments described herein includes asub-pixel circuit having a line-type architecture. A third exemplaryembodiment of the embodiments described herein includes a sub-pixelcircuit having a dot-type architecture with a plug disposed on anencapsulation layer of a respective sub-pixel. A fourth exemplaryembodiment of the embodiments described herein includes a sub-pixelcircuit having a line-type architecture with a plug disposed on anencapsulation layer of a respective sub-pixel.

Each of the embodiments described herein of the sub-pixel circuitinclude a plurality of sub-pixels with each of the sub-pixels defined byadjacent overhang structures that are permanent to the sub-pixelcircuit. The overhang structures include a conductive oxide. While theFigures depict two sub-pixels with each sub-pixel defined by adjacentoverhang structures, the sub-pixel circuit of the embodiments describedherein include a plurality of sub-pixels, such as two or moresub-pixels. Each sub-pixel has the OLED material configured to emit awhite, red, green, blue or other color light when energized. E.g., theOLED material of a first sub-pixel emits a red light when energized, theOLED material of a second sub-pixel emits a green light when energized,and the OLED material of a third sub-pixel emits a blue light whenenergized.

The overhang structures are permanent to the sub-pixel circuit. Theoverhang structures include a conductive oxide. A first configuration ofthe overhang structures includes a base portion and a top portion withthe top portion disposed on the base portion. In a firstsub-configuration, the base portion includes the conductive oxide of atleast one of a transparent conductive oxide (TCO) material or atransition metal oxide (TMO) material. The TCO material includes, but isnot limited to, one or more of indium zinc oxide (IZO), indium galliumzinc oxide (IGZO), indium tin oxide (ITO), or combinations thereof. TheTMO material includes a transition metal. The transition metal is anyelement whose atom has a partially filed d sub-shell, or which can giverise to cations with an incomplete d sub-shell. Examples of thetransition metal includes, but are not limited to, one or more of oxidesof ruthenium (Ru), vanadium (V), titanium (Ti), zinc (Zn), copper (Cu),molybdenum (Mo), or combinations thereof. In a second sub-configuration,the base portion includes a metal alloy material and the conductiveoxide of a metal oxide surface. The metal alloy material incudes, but isnot limited to, copper (Cu), Ti, aluminum (Al), molybdenum (Mo), silver(Ag), tin (Sn) or combinations thereof. The metal oxide surface includesone or more oxides of the metal alloy material.

A second configuration of the overhang structures includes the baseportion and the top portion with a body portion disposed between thebase portion and the top portion. The base portion includes theconductive oxide of at least one of the TCO material or the TMOmaterial. The body portion includes the metal alloy body and the metaloxide surface. The metal alloy body includes the metal alloy material.The top portion includes a metal material that includes, but is notlimited to, Ti, Cu, Mo, ITO, IZO, or combinations thereof.

The adjacent overhang structures defining each sub-pixel of thesub-pixel circuit of the display provide for formation of the sub-pixelcircuit using evaporation deposition and provide for the overhangstructures to remain in place after the sub-pixel circuit is formed.Evaporation deposition may be utilized for deposition of an OLEDmaterial (including a hole injection layer (NIL), a hole transport layer(HTL), an emissive layer (EML), and an electron transport layer (ETL))and cathode. One or more of an encapsulation layer, the plug, and aglobal encapsulation layer may be disposed via evaporation deposition.The overhang structures extend over a portion of the OLED material andthe cathode of the sub-pixels. The overhang structures define depositionangles, i.e., provide for a shadowing effect during evaporationdeposition, for each of the OLED material and the cathode such the OLEDmaterial does not contact the overhang structures and the cathodecontacts at least a portion of a sidewall of the base portion of theoverhang structures.

The encapsulation layer of a respective sub-pixel is disposed over thecathode with the encapsulation layer. The encapsulation layer may be ormay correspond to a local encapsulation layer. The encapsulation layermay extend under at least a portion of each of the adjacent overhangstructures. In other embodiments, which can be combined with otherembodiments described herein, the encapsulation layer may further extendalong a sidewall of each of the adjacent overhang structures. Theencapsulation layer may also be disposed over or on an upper surface ofthe top portion of the overhang structures. A global encapsulation layermay be disposed over the encapsulation layer. The plug of the third andthe fourth exemplary embodiments may be disposed between theencapsulation layer and the global encapsulation layer. In one example,the global encapsulation layer is conformal to the cathode and theoverhang structures. In another example, the global encapsulation layeris non-conformal to the cathode and the overhang structures. The globalencapsulation layer may include an inkjet sublayer and a globalencapsulation sublayer.

FIGS. 1A and 1B are schematic, cross-sectional views of a sub-pixelcircuit 100. The sub-pixel circuit 100 of FIG. 1A includes the firstconfiguration 101A of overhang structures 110. The overhang structures110 include a conductive oxide. The first configuration 101A of theoverhang structures 110 includes a base portion 110A and a top portion110B with the top portion 110B disposed on the base portion 110A. Thesub-pixel circuit 100 of FIG. 1B includes the second configuration 101Bof the overhang structures. The second configuration 101B of theoverhang structures 110 includes the base portion 110A and the topportion 110B with a body portion 110C disposed between the base portionand the top portion.

The sub-pixel circuit 100 includes a substrate 102. Metal layers 104 maybe patterned on the substrate 102 and are defined by adjacentpixel-defining layer (PDL) structures 126 disposed on the substrate 102.In one embodiment, which can be combined other embodiments describedherein, the metal layers 104 are pre-patterned on the substrate 102.E.g., the substrate 102 is a pre-patterned indium tin oxide (ITO) glasssubstrate. The metal layers 104 are configured to operate anodes ofrespective sub-pixels. The metal layers 104 include, but are not limitedto, chromium, titanium, gold, silver, copper, aluminum, ITO, orcombinations thereof, or other suitably conductive materials.

The PDL structures 126 are disposed on the substrate 102. The PDLstructures 126 include one of an organic material, an organic materialwith an inorganic coating disposed thereover, or an inorganic material.The organic material of the PDL structures 126 includes, but is notlimited to, polyimides. The inorganic material of the PDL structures 126includes, but is not limited to, silicon oxide (SiO₂), silicon nitride(Si₃N₄), silicon oxynitride (SiON), magnesium fluoride (MgF₂), orcombinations thereof. Adjacent PDL structures 126 define a respectivesub-pixel and expose the anode (i.e., metal layer 104) of the respectivesub-pixel of the sub-pixel circuit 100.

The sub-pixel circuit 100 has a plurality of sub-pixels 106 including atleast a first sub-pixel 108 a and a second sub-pixel 108 b. While theFigures depict the first sub-pixel 108 a and the second sub-pixel 108 b.The sub-pixel circuit 100 of the embodiments described herein mayinclude two or more sub-pixels 106, such as a third and a fourthsub-pixel. Each sub-pixel 106 has an OLED material 112 configured toemit a white, red, green, blue or other color light when energized.E.g., the OLED material 112 of the first sub-pixel 108 a emits a redlight when energized, the OLED material of the second sub-pixel 108 bemits a green light when energized, the OLED material of a thirdsub-pixel emits a blue light when energized, and the OLED material of afourth sub-pixel emits a other color light when energized

The overhang structures 110 are disposed on an upper surface 103 of eachof the PDL structures 126. The overhang structures 110 are permanent tothe sub-pixel circuit. Thus, organic material from lifted off overhangstructures that disrupt OLED performance would not be left behind.Eliminating the need for a lift-off procedure also increases throughput.The overhang structures 110 further define each sub-pixel 106 of thesub-pixel circuit 100. The overhang structures 110 include at least(e.g., the first configuration 101A) the base portion 110A disposed onthe upper surface 103 of each of the PDL structures 126 and the topportion 110B disposed over the base portion 110A. At least an undersidesurface 107 of the top portion 110B is wider than a top surface 105 ofthe base portion 110A to form an overhang 109. The body portion 110C ofsecond configuration 101B of the overhang structures 110 includes at abottom surface 117 with a width less than or equal to the top surface105 of the base portion 110A, and a top surface 119 with a width lessthan the underside surface 107 of the top portion 110B.

The underside surface 107 of the top portion 110B larger than the topsurface 105 of the base portion 110A forming the overhang 109 allows forthe top portion 110B to shadow the base portion 110A. The shadowing ofthe overhang 109 provides for evaporation deposition each of the OLEDmaterial 112 and a cathode 114. As further discussed in thecorresponding descriptions of FIGS. 2A and 2B, the shadowing effect ofthe overhang structures 110 define a OLED angle θ_(OLED) (shown in FIGS.2A and 2B) of the OLED material 112 and a cathode angle θ_(cathode)(shown in FIGS. 2A and 2B) of the cathode 114. The OLED angle θ_(OLED)of the OLED material 112 and the cathode angle θ_(cathode) of thecathode 114 may result from evaporation deposition of the OLED material112 and the cathode 114.

In a first sub-configuration 125A of the first configuration 101A of theoverhang structures 110, as shown in FIG. 1A, the base portion 110Aincludes a conductive oxide of at least one of the TCO material or theTMO material. The TCO material includes, but is not limited to, one ormore of IZO, IGZO, ITO, or combinations thereof. The TMO materialincludes a transition metal. The transition metal is any element whoseatom has a partially filed d sub-shell, or which can give rise tocations with an incomplete d sub-shell. Examples of the TMO materialinclude, but are not limited to, one or more of oxides of Ru, V, Ti, Zn,Cu, Mo, or combinations thereof. In a second sub-configuration 125B ofthe first configuration 101A of the overhang structures 110, as shown inFIG. 2B, the base portion 110A includes a metal alloy material and theconductive oxide of a metal oxide surface 130. The metal alloy materialthat incudes, but is not limited to, Cu, Ti, Al, Mo, Ag, Sn orcombinations thereof. The metal oxide surface 130 includes one or moreoxides of the metal alloy material. A second configuration 101B of theoverhang structures 110, the body portion 110C includes a metal alloybody 128 with a metal oxide surface 130. The metal alloy body 128includes the metal alloy material. The top portion 110B includes a metalmaterial that includes, but is not limited to, Ti, Cu, Mo, ITO, IZO orcombinations thereof.

The OLED material 112 may include one or more of a HIL, a HTL, an EML,and an ETL. The OLED material 112 is disposed on the metal layer 104. Insome embodiments, which can be combined with other embodiments describedherein, the OLED material 112 is disposed on the metal layer 104 andover a portion of the PDL structures 126. The cathode 114 is disposedover the OLED material 112 of the PDL structures 126 in each sub-pixel106. The cathode 114 is be disposed on a portion of a sidewall 111 ofthe base portion 110A. The cathode 114 includes a conductive material,such as a metal. E.g., the cathode 114 includes, but is not limited to,chromium, Ti, Al, ITO, or a combination thereof. In some embodiments, asshown in FIG. 1B, which can be combined with other embodiments describedherein, at least one of the OLED material 112 or the cathode 114 aredisposed over an upper surface 115 of the top portion 110B of theoverhang structures 110

The base portion 110A including at least one of the TCO material or theTMO material provides allows for the base portion 110A to be exposed toan oxygen-containing plasma and remain conductive. Exposing the overhangstructures 110 to the oxygen-containing plasma, i.e., oxidizing theoverhang structures 110, removes organic impurities, such as a surfacemonolayer, that may remain on the sub-pixel circuit 100 prior todeposition of the OLED material 112. The TCO material, the TMO material,or the metal alloy material having the metal oxide surface 130 of thebase portion 110A allow the overhang structures 110 to remainconductive. The conductive base portion 110A ensures permanentconnection to the cathode 114.

Each sub-pixel 106 includes an encapsulation layer 116. Theencapsulation layer 116 may be or may correspond to a localencapsulation layer. The encapsulation layer 116 of a respectivesub-pixel is disposed over the cathode 114 (and OLED material 112) withthe encapsulation layer 116 extending under at least a portion of eachof the overhang structures 110. In some embodiments, as shown in FIG.1B, which can be combined with other embodiments described herein, theencapsulation layer 116 extends along a sidewall of each of the overhangstructures 110. In other embodiments, as shown in FIG. 1B, which can becombined with other embodiments described herein, the encapsulationlayer 116 extends along a sidewall and is disposed on or over of theupper surface 115 of the top portion 110B each of the overhangstructures 110. The encapsulation layer 116 is disposed over the cathode114. The encapsulation layer 116 includes the non-conductive inorganicmaterial, such as a silicon-containing material. The silicon-containingmaterial may include Si₃N₄ containing materials.

In embodiments including one or more capping layers, the capping layersare disposed between the cathode 114 and the encapsulation layer 116.E.g., as shown in FIG. 1A, a first capping layer 121 and a secondcapping layer 123 are disposed between the cathode 114 and theencapsulation layer 116. While FIG. 1A depicts the sub-pixel circuit 100having one or more capping layers, each of the embodiments describedherein may include one or more capping layers disposed between thecathode 114 and the encapsulation layer 116. The first capping layer 121may include an organic material. The second capping layer 123 mayinclude an inorganic material, such as lithium fluoride. The firstcapping layer 121 and the second capping layer 123 may be deposited byevaporation deposition.

A global encapsulation layer 120 may be disposed over the encapsulationlayer 116. A plug 122 of the third and the fourth exemplary embodiments(as depicted by the second sub-pixel 108 b) may be disposed between theencapsulation layer 116 and the global encapsulation layer 120. In oneexample, as shown in FIG. 1A, the global encapsulation layer isconformal to the cathode 114 and the overhang structures 110. In anotherexample, as shown in FIG. 1B, the global encapsulation layer 120 isnon-conformal to the cathode 114 and the overhang structures 110. Theglobal encapsulation layer may include an inkjet sublayer 118 a and aglobal encapsulation sublayer 118 b. The inkjet sublayer 118 a mayinclude an acrylic material.

The third and fourth exemplary embodiments (as shown depicted by thesecond sub-pixel of FIGS. 1A and 1B) include plugs 122 disposed over theencapsulation layers 116. Each plug 122 is disposed in a respectivesub-pixel 106 of the sub-pixel circuit 100. The plugs 122 may bedisposed over the upper surface 115 of the top portion 110B of theoverhang structures 110. The plugs 122 include, but are not limited to,a photoresist, a color filter, or a photosensitive monomer. The plugs122 have a plug transmittance that is matched or substantially matchedto an OLED transmittance of the OLED material 112. The plugs 122 mayeach be the same material and match the OLED transmittance. The plugs122 may be different materials that match the OLED transmittance of eachrespective sub-pixel of the plurality of sub-pixels 106. The matched orsubstantially matched resist transmittance and OLED transmittance allowfor the plugs 122 to remain over the sub-pixels 106 without blocking theemitted light from the OLED material 112. The plugs 122 are able toremain in place and thus do not require a lift off procedure to beremoved from the sub-pixel circuit 100. Additional pattern resistmaterials disposed over the formed sub-pixels 106 at subsequentoperations are not required because the plugs 122 remain. Eliminatingthe need for a lift-off procedure on the plugs 122 and the need foradditional pattern resist materials on the sub-pixel circuit 100increases throughput.

FIG. 1C is a schematic, top sectional view of a sub-pixel circuit 100having a dot-type architecture 101C. The dot-type architecture 101C maycorrespond to the first or third exemplary embodiments of the sub-pixelcircuit 100. FIG. 1D is a schematic, cross-sectional view of a sub-pixelcircuit 100 having a line-type architecture 101D. The line-typearchitecture 101D may correspond to the second or fourth exemplaryembodiments of the sub-pixel circuit 100. Each of the top sectionalviews of FIGS. 1C and 1D are taken along section line 1′-1′ of FIGS. 1Aand 1B.

The dot-type architecture 101C includes a plurality of pixel openings124A. Each of pixel opening 124A is surrounded by the overhangstructures 110 that define each of the sub-pixels 106 of the dot-typearchitecture 101C. The line-type architecture 101D includes a pluralityof pixel openings 124B. Each of pixel opening 124B is abutted byoverhang structures 110 that define each of the sub-pixels 106 of theline-type architecture 101D. The overhang structures 110 include aconductive oxide.

FIGS. 2A and 2B are schematic, cross-sectional view of an overhangstructure 110 of a sub-pixel circuit 100 of FIGS. 1A and 1B. Theoverhang structure 110 of FIG. 2A includes the second sub-configuration125B of the first configuration 101A. The base portion 110A of theoverhang structure 110 of the second sub-configuration 125A includes themetal alloy material and the conductive oxide of the metal oxide surface130. The cathode 114 contacts the metal oxide surface 130. The overhangstructure 110 of FIG. 2B includes the second configuration 101B. In someembodiments, which can be combined with other embodiments describedherein, as shown in FIG. 2B, the body portion 110C includes more thanone metal alloy layers, such as a first metal alloy layer 207, a secondmetal alloy layer 209, and a third metal alloy layer 211. Each of thefirst metal alloy layer 207, the second metal alloy layer 209, and thethird metal alloy layer 211 includes the metal alloy material thatincudes, but is not limited to, Cu, Ti, Al, Mo, Ag, Sn or combinationsthereof. In the embodiments, the first metal alloy layer and the thirdmetal alloy layer 211 may be the same metal alloy material. In oneexample, the first metal alloy layer and the third metal alloy layer 211include Mo and the second metal alloy layer 209 includes Ti.

The top portion 1106 includes an underside edge 206 and an overhangvector 208. The underside edge 206 extends past the sidewall 111 of thebase portion 110A such that the overhang structures 110 extend over aportion of the OLED material 112 and the cathode 114. The shadowing ofthe overhang 109 provides for evaporation deposition each of the OLEDmaterial 112 and the cathode 114, and in some embodiments, the firstcapping layer 121 and/or the second capping layer 123. Each overhangstructure 110 includes the overhang 109 defined by an overhang width 203and an overhang depth 205. The overhang width 203 is from the sidewall111 of the base portion 110A to the underside edge 206, i.e., exterioredge, of the top portion 1106 of the overhang structure 110. Theoverhang depth 205 is from the PDL 126 to the underside edge 206.

The overhang vector 208 is defined by the underside edge 206 and the PDLstructure 126. The OLED material 112 is disposed over the anode and overa shadow portion 210 of the PDL structure 126. The OLED material 112forms an OLED angle θ_(OLED) between an OLED vector 212 and the overhangvector 208. The OLED vector 212 is defined by an OLED edge 214 extendingunder the top portion 1106. In one embodiment, which can be combinedwith other embodiments described herein, a HIL 204 of the OLED material112 included. In the embodiment including the HIL 204, the OLED material112 includes the HTL, the EML, and the ETL. The HIL 204 forms an HILangle θ_(HIL) between a HIL vector 216 and the overhang vector 208. TheHIL vector 216 is defined by an HIL edge 218 extending under the topportion 1106.

The cathode 114 is disposed on the OLED material 112 and over the shadowportion 210 of the PDL structure 126. The cathode 114 is disposed on aportion of the sidewall 111 of the base portion 110A. The cathode 114forms a cathode angle θ_(cathode) between a cathode vector 224 and theoverhang vector 208. The cathode vector 224 is defined by a cathode edge226 at least extending under the top portion 1106. The encapsulationlayer 116 is disposed over the cathode 114 (and OLED material 112) withthe encapsulation layer 116 extending under at least under the topportion 110B.

During evaporation deposition of the OLED material 112, the undersideedge 206 of the top portion 110B defines the position of the OLED edge214. E.g., the OLED material 112 is evaporated at an OLED maximum anglethat corresponds to the OLED vector 212 and the underside edge 206ensures that the OLED material 112 is not deposited past the OLED edge214. In embodiments with the HIL 204, the underside edge 206 of the topportion 110B defines the position of the HIL edge 218. E.g., the HIL 204is evaporated at an HIL maximum angle that corresponds to the HIL vector216 and the underside edge 206 ensures that HIL 204 is not depositedpast the HIL edge 218. During evaporation deposition of the cathode 114,the underside edge 206 of the top portion 110B defines the position ofthe cathode edge 226. E.g., the cathode 114 is evaporated at a cathodemaximum angle that corresponds to the cathode vector 224 and theunderside edge 206 ensures that the cathode 114 is not deposited pastthe cathode edge 226. The OLED angle θ_(OLED) is less than the cathodeangle θ_(cathode). The HIL angle θ_(HIL) is less than the OLED angleθ_(OLED).

FIG. 3 is a flow a flow diagram of a method 300 for forming a sub-pixelcircuit 100. FIGS. 4A-4H are schematic, cross-sectional views of aportion 400 of the substrate 102 during the method 300 for forming thesub-pixel circuit 100 according embodiments described herein. FIGS. 4A,4C, 4E, and 4G depict embodiments of the method 300 for forming thesub-pixel circuit 100 having overhang structures 110 of the firstconfiguration 101A. FIGS. 4B, 4D, 4F, and 4H depict embodiments of themethod 300 for forming the sub-pixel circuit 100 having overhangstructures 110 of the second configuration 101B. The method 300 may beutilized to fabricate a sub-pixel circuit 100 of one of the first,second, third, or fourth exemplary embodiments. The portion 400corresponds to a sub-pixel 106, such as a first sub-pixel 108 a, of thesub-pixel circuit 100.

At operation 301, as shown in FIGS. 4A and 4B, an overhang layer stack402 is disposed over the substrate 102. In embodiments of the firstconfiguration 101A, as shown in FIG. 4A, the overhang layer stack 402includes a base layer 402A corresponding to the base portion 110A and atop layer 402B corresponding to the top portion 110B. In embodiments ofthe second configuration 101B, as shown in FIG. 4B, the overhang layerstack 402 includes the base layer 402A, a body layer 402C correspondingto the body portion 110C, and the top layer 402B. The base layer 402A isdisposed over the PDL structures 126 and the metal layers 104. The baselayer 402A includes at least one of the TCO material or the TMO materialof the first sub-configuration 125A or the metal alloy material of thesecond sub-configuration 125B. The body layer 402C incudes, the metalalloy material. The top layer 402B includes the metal material.

At operation 302, as shown in FIGS. 4C and 4D, a resist 404 is disposedand patterned. The resist 404 is disposed over the top layer 402B. Theresist 404 is a positive resist or a negative resist. The chemicalcomposition of the resist 404 determines whether the resist is apositive resist or a negative resist. The resist 404 is patterned toform one of a pixel opening 124A of the dot-type architecture 101C or apixel opening 124B of the line-type architecture 101D of a sub-pixel106. The patterning is one of a photolithography, digital lithographyprocess, or laser ablation process.

At operation 303, as shown in FIGS. 4E and 4F, portions of the overhanglayer stack 402 are etched. The portions of the top layer 402B and thebase layer 402A (and the body layer 402C of the second configuration101B) exposed by the pixel opening 124A, 124B are removed with an etchprocess. Operation 303 forms the overhang structures 110 of thesub-pixel 106. The etch process to form the overhang structures 110 ofthe first configuration 101A utilizes a top layer etch chemistry and abase layer etch chemistry. The etch process to form the overhangstructures 110 of the second configuration 101B utilizes the top layeretch chemistry, a body layer etch chemistry, and the base layer etchchemistry. The top layer etch chemistry includes a dry etch chemistry.The body layer etch chemistry and the base layer include a wet etchchemistry. In some embodiments, which can be combined with otherembodiments described herein, the body layer etch chemistry and the baselayer includes the same wet etch chemistry. The wet etch chemistryincludes, but is not limited to sulfuric acid, nitric acid, and aceticacid, or combinations thereof.

In the embodiments of the first configuration 101A, to form the baseportion 110A and the top portion 110B of the overhang structures 110,the top layer etch chemistry, e.g., dry etch chemistry, and the baselayer etch chemistry are selected based on the compositions of the toplayer 402B and the base layer 402A. The etch selectivity between thematerials of the top layer 402B and the base layer 402A and the etchprocess to remove the exposed portions of the top layer 402B and thebase layer 402A provide for an underside surface 107 of the top portion110B being wider than a top surface 105 of the base portion 110A to formthe overhang 109.

In the embodiments of the second configuration 101B, to form the baseportion 110A, the body portion 110C, and the top portion 110B of theoverhang structures 110, the top layer etch chemistry, e.g., dry etchchemistry, and the body layer etch chemistry and the base layer etchchemistry are selected based on the compositions of the top layer 402B,the body layer 402C, and the base layer 402A. The etch selectivitybetween the materials of the top layer 402B, the body layer 402C, andthe base layer 402A and the etch process to remove the exposed portionsof the top layer 402B and the base layer 402A provide for an undersidesurface 107 of the top portion 110B being wider than a top surface 105of the base portion 110A to form the overhang 109. The wet etchchemistry will etch portions of the body layer 402C faster than baselayer 402A. The shadowing of the overhang 109 provides for evaporationdeposition the OLED material 112 and the cathode 114. After operation303 the resist 404 is removed.

The TCO material and/or the TMO material of the base layer 402A allowthe body layer 402C and the base layer 402A to be etched simultaneouslyas the TCO material and/or the TMO material will etch at a lower ratethan the metal alloy material of the body layer 402C. The base layer402A also protects the metal layers 104 from exposure to etchant whenthe top layer 402B, and in some embodiments, the body layer 402C areetched as a thin layer of the base layer 402A may remain after the toplayer etch chemistry and the body layer etch chemistry are used. Thebase layer etch chemistry may be used to etch the thin, protective layerremaining from the base layer 402A. The selection of at least the TCOmaterial and/or the TMO material of the base layer 402A, the metalmaterial of the top layer 402B (in some embodiments the metal alloymaterial of the body layer 402C), and the chemistries of the etchprocess provide for formation of the overhang structures 110 with auniform overhang depth 205. The overhang structures 110 of the sub-pixelcircuit 100 include the overhang width 203 about 0.5 μm (micrometers) toabout 1 μm. Each overhang width 203 of the overhang structures 110 arewithin about 15 percent of each other.

At operation 304, the overhang structures 110 are oxidized. The overhangstructures 110 are oxidized via exposure to an oxygen-containing plasma,such as an O₂ plasma. In the second sub-configuration 125B of the firstconfiguration 101A, as shown in FIGS. 2A, and 4G, exposure of the baseportion 110A to an oxygen-containing plasma forms the metal oxidesurface 130 on the metal alloy material. In embodiments of the secondconfiguration 101B, as shown in FIGS. 1B, 2B, and 4H, exposure of thebody portion 110C to an oxygen-containing plasma forms a metal oxidesurface 130 on a metal alloy body 128 formed from operation 303.Exposing the overhang structures 110 to the oxygen-containing plasma,i.e., oxidizing the overhang structures 110, removes organic impurities,such as a surface monolayer, that may remain on the sub-pixel circuit100 prior to deposition of the OLED material 112.

At operation 305, as shown in FIGS. 4G and 4H, the OLED material 112,the cathode 114, and the encapsulation layer 116 are deposited. Theshadowing of the overhang 109 provides for evaporation deposition eachof the OLED material 112 and the cathode 114. As further discussed inthe corresponding description of FIGS. 2A and 2B, the shadowing effectof the overhang structures 110 define the OLED angle θ_(OLED) of theOLED material 112 and the cathode angle θ_(cathode) (of the cathode 114.The OLED angle θ_(OLED) of the OLED material 112 and the cathode angle Acathode of the cathode 114 result from evaporation deposition of theOLED material 112 and the cathode 114. In some embodiments, which can becombined with other embodiments described herein, one or more cappinglayer such as the first capping layer 121 and the second capping layer123 are disposed between the cathode 114 and the encapsulation layer116. At operation 306, a global encapsulation layer 120 is disposed. Insome embodiments, as shown in FIG. 4G, the plug 122 is disposed betweenthe encapsulation layer 116 and the global encapsulation layer 120. Theglobal encapsulation layer 120 may include the inkjet sublayer 118 a andthe global encapsulation sublayer 118 b.

In summation, described herein relate to sub-pixel circuits and methodsof forming sub-pixel circuits that may be utilized in a display such asan organic light-emitting diode (OLED) display. The adjacent overhangstructures defining each sub-pixel of the sub-pixel circuit of thedisplay provide for formation of the sub-pixel circuit using evaporationdeposition and provide for the overhang structures to remain in placeafter the sub-pixel circuit is formed. Evaporation deposition may beutilized for deposition of an OLED material and cathode. The overhangstructures define deposition angles, i.e., provide for a shadowingeffect during evaporation deposition. The base portion including atleast one of the TCO material, the TMO material, or the metal alloymaterial having the metal oxide surface provides allows for the baseportion to be exposed to an oxygen-containing plasma and remainconductive. Exposing the overhang structures to the oxygen-containingplasma, i.e., oxidizing the overhang structures, removes organicimpurities, such as a surface monolayer, that may remain on thesub-pixel circuit 100 prior to deposition of the OLED material. The TCOmaterial, the TMO material, or the metal alloy material having the metaloxide surface allows the overhang structures to remain conductive toensure that the base portion and the cathode are permanently connected.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

What is claimed is:
 1. A device, comprising: a substrate; overhangstructures disposed over the substrate; a plurality of sub-pixels, eachsub-pixel is defined by a first overhang structure and a second overhangstructure adjacent to each other, the first overhang structure and thesecond overhang structure having: a base portion disposed over thesubstrate, the base portion comprising a first composition; and a topportion disposed over the base portion, the top portion including afirst extension and a second extension having a bottom surface widerthan a top surface of the base portion, all of the bottom surface of thetop portion including the first extension and the second extension isplanar to all of the top surface of the base portion, the top portioncomprising a metal of a second composition different than the firstcomposition, wherein: the first extension of the top portion of thefirst overhang structure extends laterally past the base portion and isdisposed entirely above sidewalls of the base portion; and the secondextension of the top portion of the second overhang structure extendslaterally past the base portion and is disposed entirely above thesidewalls of the base portion; an anode; an organic light-emitting diode(OLED) material disposed over the anode; and a cathode disposed over theOLED material, the cathode extending under the first extension of thetop portion of the first overhang structure and the second extension ofthe top portion of the second overhang structure, wherein a cathodematerial of the cathode is different from the second composition; anencapsulation layer disposed over the cathode, wherein the encapsulationlayer extends under the first extension of the top portion of the firstoverhang structure and the second extension of the top portion of thesecond overhang structure past the cathode along the sidewall of thebase portion, and contacts the bottom surface of the top portion.
 2. Thedevice of claim 1, wherein the second composition comprises a metalalloy material.
 3. The device of claim 2, wherein the metal alloymaterial comprises copper (Cu), titanium (Ti), aluminum (Al), molybdenum(Mo), silver (Ag), tin (Sn), or combinations thereof.
 4. The device ofclaim 1, wherein the first composition comprises at least one of: atransition metal; a transition metal oxide (TMO) material; or atransparent conductive oxide (TCO) material.
 5. The device of claim 4,wherein: the transition metal comprises ruthenium (Ru), vanadium (V),titanium (Ti), zinc (Zn), copper (Cu), molybdenum (Mo), or combinationsthereof; the TMO material comprises one or more oxides of the transitionmetal; and the TCO material comprises one or more of indium zinc oxide(IZO), indium gallium zinc oxide (IGZO), indium tin oxide (ITO), orcombinations thereof.
 6. The device of claim 1, wherein the cathodedirectly contacts the base portion.
 7. The device of claim 1, whereineach sub-pixel further comprises a plug disposed over the encapsulationlayer, the plug having a plug transmittance that is matched orsubstantially matched to an OLED transmittance of the OLED material. 8.The device of claim 1, further comprising a global encapsulation layerdisposed over the first overhang structure, the second overhangstructure, and the encapsulation layer.
 9. The device of claim 1,wherein the device comprises a dot-type architecture or a line-typearchitecture.
 10. The device of claim 1, wherein the substrate is apre-patterned indium tin oxide (ITO) glass substrate.
 11. A device,comprising: a substrate; overhang structures disposed over thesubstrate; a plurality of sub-pixels, each sub-pixel is defined by afirst overhang structure and a second overhang structure adjacent toeach other, the first overhang structure and the second overhangstructure having: a base portion disposed over the substrate, the baseportion comprising a first composition; and a top portion disposed overthe base portion, the top portion including a first extension and asecond extension having a bottom surface wider than a top surface of thebase portion, all of the bottom surface of the top portion including thefirst extension and the second extension is planar to all of the topsurface of the base portion, the top portion comprising a metal of asecond composition different than the first composition, the metal is ametal alloy material, wherein: the first extension of the top portion ofthe first overhang structure extends laterally past the base portion andis disposed entirely above sidewalls of the base portion; and the secondextension of the top portion of the second overhang structure extendslaterally past the base portion and is disposed entirely above thesidewalls of the base portion; an anode; an organic light-emitting diode(OLED) material disposed over the anode; and a cathode disposed over theOLED material, the cathode extending under the first extension of thetop portion of the first overhang structure and the second extension ofthe top portion of the second overhang structure, wherein a cathodematerial of the cathode is different from the second composition; anencapsulation layer disposed over the cathode, wherein the encapsulationlayer extends under the first extension of the top portion of the firstoverhang structure and the second extension of the top portion of thesecond overhang structure past the cathode along the sidewall of thebase portion, and contacts the bottom surface of the top portion. 12.The device of claim 11, wherein the metal alloy material comprisescopper (Cu), titanium (Ti), aluminum (Al), molybdenum (Mo), silver (Ag),tin (Sn), or combinations thereof.
 13. The device of claim 11, whereinthe first composition comprises at least one of: a transition metal; atransition metal oxide (TMO) material; or a transparent conductive oxide(TCO) material.
 14. The device of claim 13, wherein: the transitionmetal comprises ruthenium (Ru), vanadium (V), titanium (Ti), zinc (Zn),copper (Cu), molybdenum (Mo), or combinations thereof; the TMO materialcomprises one or more oxides of the transition metal; and the TCOmaterial comprises one or more of indium zinc oxide (IZO), indiumgallium zinc oxide (IGZO), indium tin oxide (ITO), or combinationsthereof.
 15. The device of claim 11, wherein the cathode directlycontacts the base portion.
 16. The device of claim 11, wherein eachsub-pixel further comprises a plug disposed over the encapsulationlayer, the plug having a plug transmittance that is matched orsubstantially matched to an OLED transmittance of the OLED material. 17.The device of claim 11, further comprising a global encapsulation layerdisposed over the first overhang structure, the second overhangstructure, and the encapsulation layer.
 18. The device of claim 11,wherein the device comprises a dot-type architecture or a line-typearchitecture.
 19. The device of claim 11, wherein the substrate is apre-patterned indium tin oxide (ITO) glass substrate.
 20. A device,comprising: a substrate; overhang structures disposed over thesubstrate; a plurality of sub-pixels, each sub-pixel is defined by afirst overhang structure and a second overhang structure adjacent toeach other, the first overhang structure and the second overhangstructure having: a base portion disposed over the substrate, the baseportion comprising a first composition; and a top portion disposed overthe base portion, the top portion including a first extension and asecond extension having a bottom surface wider than a top surface of thebase portion, all of the bottom surface of the top portion including thefirst extension and the second extension is planar to all of the topsurface of the base portion, the top portion comprising a metal of asecond composition different than the first composition, wherein: thefirst extension of the top portion of the first overhang structureextends laterally past the base portion and is disposed entirely abovesidewalls of the base portion; and the second extension of the topportion of the second overhang structure extends laterally past the baseportion and is disposed entirely above the sidewalls of the baseportion; an anode; an organic light-emitting diode (OLED) materialdisposed over the anode; and a cathode disposed over the OLED material,the cathode extending under the first extension of the top portion ofthe first overhang structure and the second extension of the top portionof the second overhang structure, wherein a cathode material of thecathode is different from the second composition and the cathodedirectly contacts the base portion; an encapsulation layer disposed overthe cathode, wherein the encapsulation layer extends under the firstextension of the top portion of the first overhang structure and thesecond extension of the top portion of the second overhang structurepast the cathode along the sidewall of the base portion, and contactsthe bottom surface of the top portion.